In general, a Cyclic Delay Diversity (CDD) scheme is adopted for an Orthogonal Frequency Division Multiplexing (OFDM) system to thereby improve frequency selectivity of a channel, so that a coding gain is improved through a channel encoding scheme.
In the CDD scheme, the frequency selectivity of the channel vary according to a cyclic delay value. When a signal is transmitted/received via a multi-path delay channel in the OFDM system using a plurality of transmitting antennas and a signal receiving antenna in the case where it is assumed that a channel estimation is perfectly performed, a cyclic delay value is required to be greater than or equal to a maximum delay spread so as to remove correlation between signals transmitted from each of the plurality of transmitting antennas.
However, in the case where the channel estimation is not perfectly performed, correlation between Signal-to-Interference and Noise Ratio (SINR) gain due to the diversity effect and SINR loss due to channel estimation error exists. Specifically, in the case where Root Mean Square (RMS) delay spread of a channel is relatively great, since the channel has already achieved significant diversity effect required for the performance improvement, additional performance improvement is not highly expected through the CDD scheme. Conversely, in the case where the CDD scheme is adopted, the diversity effect is not achieved, however, performance of channel estimation is likely to be deteriorated, thereby decreasing the entire performance.